Mint plant named ‘McKenzie’

ABSTRACT

A new and distinct peppermint plant ‘McKenzie’ characterized by its upright growth habit, vigorous and abundant root growth, resistance to Spider Mites ( Tetranychus urticae ), Mint rust ( Puccinia menthe  Pers), Mint wilt ( Verticillium dahliae  and  Verticillium albo - atrum ), and a distinct flower spike with mostly pinkish white petals and consistent oil quality throughout its phases of maturity.

Latin name of the genus and species of the plant claimed:Mentha×piperita.

Variety denomination: ‘McKenzie’.

FIELD OF THE INVENTION

The present invention relates to a new and distinct peppermint plantbotanically known as Mentha×piperita. The new variety has been named‘McKenzie’ and will be referred as such hereafter.

BACKGROUND OF THE INVENTION

The new peppermint plant of the present invention was developed in aneffort to cultivate a peppermint variety exhibiting an upright growthhabit, vigorous and abundant root growth, greater resistance to Spidermites (Tetranychus urticae), Mint rust (Puccinia menthe Pers) andVerticillium wilt (Verticillium dahliae and V. albo-atrum). Further,‘McKenzie’ produces a peppermint oil that varies minimally in oilprofile based on plant maturity.

The inventor explored ways of creating peppermint hybrids throughconventional crosses from the ‘Black Mitcham’ (Menthapiperita)—not-patented—parent plants without the use of chemicals toincrease ploidy. The method relied on adjusting environmental conditionsto generate viable pollen. Using this method, several seedlings weregenerated in 1996 using two ‘Black Mitcham’ peppermint plants asparents.

The resulting selection has been under continuous evaluation at the A.M. Todd facility located in Jefferson, Oreg., since 1996 and has beenasexually propagated through stem, propagules and rhizome cuttings. Theresulting propagules have remained identical to the parent plant inappearance, resistance to the common diseases encountered by mintplants, peppermint oil quality and vigorous root growth.

SUMMARY OF THE INVENTION

The present invention relates to a novel peppermint plant named‘McKenzie’ characterized by its more upright growth habit as shown bytaller growth with thicker stems, when compared to commercial peppermintvarieties, more abundant and vigorous root growth and resistance to Mintrust (Puccinia menthe Pers), Verticillium wilt (Verticillium dahliae andV. albo-atrum), and Spider mites (Tetranychus urticae). The peppermintoil profile of ‘McKenzie’ is also similar throughout its maturity whengrown in Oregon and Washington.

BRIEF DESCRIPTION OF THE PHOTOGRAPHS

The accompanying color photographs of ‘McKenzie’ show the new variety:

FIG. 1: shows cuttings of the claimed plant ‘McKenzie’ including itsfoliage and inflorescences.

FIG. 2: shows the mature leaves of ‘McKenzie’.

FIG. 3: shows the flower spike of ‘McKenzie’ and its flower whorlshaving mostly pinkish-white flower petals.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is a new and distinct variety of peppermint planthaving the following characteristics that, in combination, are notexhibited in other peppermint plants:

1. More upright growth habit;

2. More vigorous and abundant root growth;

3. Improved resistance to Spider mites (Tetranychus urticae);

4. Oil profile that shows little variability based on plant maturity.

5. Improved resistance to Mint rust (Puccinia menthe Pers);

6. Improved resistance to Verticillium wilt (Verticillium dahliae and V.albo-artum).

‘McKenzie’ is an herbaceous perennial with an upright shrubby growthhabit. This facilitates harvesting and thereby reduces costs. Theobserved plants were two years old and were grown outdoors in westernOregon, in a silt-loam soil. Based on an initial May planting density of8,000 plants per acre, a new ‘McKenzie’ rootstock field fills in bymid-June. The density of rhizomes from this acre of rootstock allows fora 15 to 1 expansion the following year compared to 10 to 1 for ‘BlackMitcham.’ Numerous branching stems are produced each year with aneventual height between 70-90 cm. The approximate plant spread is in therange of 14-24 cm reflecting a size measurement half way up the plantduring bloom on a managed field plot. Measurements taken at differenttimes of the year, on different locations of the plants, under differentcrop management regimes will vary. As ‘McKenzie’ is a rhizomatousperennial; it is not possible to specify the accurate dimensions of onesingle plant because the differentiation of where one plant terminatesand another begins is unknown. At the end of one growing season, it isestimated that one rooted cutting will have spread through a six squarefoot area. When compared to ‘Black Mitcham’, the industry standard,which is not patented and has been commercially grown for hundreds oryears, ‘McKenzie’ is more upright in its growth habit, taller withthicker stems (due to a large extent to the highly lignified stems whichreduces lodging), larger leaves and a lighter green color with lessanthocyanin pigment development under similar growing conditions.

‘McKenzie’ has a square stem, in the range of 6 mm on a side, comparedto the average 4.5 mm stem of ‘Black Mitcham.’ Stems and leaves,especially along leaf veins, are sparsely pubescent, more so than ‘BlackMitcham.’ This increased stem thickness results in reduced field lodgingand a stronger overall stem. Based on flowering ‘McKenzie’ matures atapproximately the same time as ‘Black Mitcham.’ ‘McKenzie’ also featuresthe additional benefit of vigorous and abundant root growth, whichresults in more rapid acreage expansion and reduction in planting costs.As compared to the peppermint plant ‘Clackamas’, which is disclosed inco-pending application No. 10/193,213, ‘McKenzie’ has a substantiallyelongated flower spike, thicker stems, darker leaf color and, on averagea taller growth habit with larger leaves.

All color descriptions according The R.H.S. Colour Chart. In botanicalterms, ‘McKenzie’ has a distinct flower spike that is quite elongated ascompared to other peppermints and can be up to 30 cm long under somegrowing conditions when measured from the lowermost verticillaster tothe tip. The number of paired flower whorls, or verticillasters, canvary from 8 to 20. The first internode between verticiels varies from1.8 to 4.0 cm. Flower petal color is much lighter than ‘Black Mitcham’.The petals are mostly pinkish-white, but have a very slight lavendercast to them. The leaves half way up the main stem are approximately 7.5cm long by 2.4 cm wide and have an ovate shape with a serrate margin.The leaves are oppositely arranged on the stem with an equilateral base,an acute apex, and serrate margin. Ventral leaf surface color is 139A(Green Group), dorsal color is 137B (Green Group), petiole color is 147C(Yellow-green Group). Stem color is 146C (Yellow-Green Group) near thebase and gradually becomes more purple until the color at the apex is187A (Greyed-Purple Group). The fragrance is peppermint-like.

The flowers of ‘McKenzie’ contain a 4-lobed, nearly regular corolla 73D(Red-purple Group) with a short tube, 8 mm long from the base of thecalyx to the tip of the forked white stigma. The calyx generally has anaverage of five ciliate teeth fused at the base forming a short tube andis 4 mm long. The calyx, peduncle and pedicel colors are 187A(Greyed-purple Group). Each flower has one pistil with a 7 mm long whitestyle and four epipetalous stamens that may be exerted with 4 mm longwhite filaments. The white anthers are less that 1 mm. Pollen color is10D (Yellow Group). The formation of seed is a rare event. There is noobvious flower fragrance and the plant does not produce fruit or seed.

The oil produced by ‘McKenzie’ is of a typical peppermint type. Incontrast to ‘Black Mitcham’, the oil profile of the ‘McKenzie’ varieslittle with plant maturity. This feature allows for increased yield dueto flexible harvest timing during a single season without significantchanges occurring to its oil profile. ‘McKenzie’ has an herbage yield ofapproximately 70 lbs./acre and an essential oil quality of peppermintoil having a 10 to 20 percent higher menthol content than standard‘Black Mitcham’ peppermint.

‘McKenzie’ has been grown and observed under 3 different fieldconditions as well as under greenhouse conditions. As with all plants,the traits have varied depending on location. These differences can beattributed to varying climates, soils, fertilizers and water regimes.However, ‘McKenzie’ remains distinct from other peppermint plants in itscharacteristics. The resistance to the diseases identified above ispresented in Table I. The results were gathered from a study performedin western Oregon and show the comparison of ‘McKenzie’ to ‘BlackMitcham’ according to the mean number of rust pustules per leaf, meannumber of Verticillium strikes per plot and mean number of spider mitesper leaf during three years of analysis.

TABLE 1 Mean Number Mean Number Mean Number of Rust Pistules ofVerticillium of Spider Mites per leaf strikes per plot per leaf Aug. 15,1999 ‘MCKENZIE’ 0.00 0.00 0.75 ‘Black Mitchum’ 40.30 9.25 8.25 Aug. 22,2000 ‘MCKENZIE’ 0.00 0.75 0.58 ‘Black Mitchum’ 183.25 17.00 10.00 Aug.26, 2001 ‘MCKENZIE’ 0.25 1.75 0.25 ‘Black Mitchum’ 81.25 30.50 11.25

As illustrated by Table I, ‘McKenzie’ is significantly more resistant tothe diseases shown. For example, although the incidence of Mint Rustvaried overall according to the three years shown due to differences inannual growing conditions, ‘McKenzie’ consistently showed much greaterresistance to Puccinia menthe Pers when compared to the mean number ofRust Pustules per leaf. In fact, Mint Rust was almost eliminated.Similarly, the number of mean strikes per plot for Verticillium dahliaeand Verticillium albo-atrum was markedly reduced by ‘McKenzie’ whencompared to ‘Black Mitcham.’ In the case of Tetranychus urticae, the mannumber of Spider Mites per leaf was, again, almost eliminated incomparison to ‘Black Mitcham’.

While the plant identified in the present invention has been describedas it relates to a specific embodiment, it is understood that thisapplication is intended to cover other variations, uses and adaptationsthat may arise under different environmental conditions.

What is claimed is:
 1. A new and distinct variety of peppermint plant,substantially as shown and described.